The present invention relates to switching devices. In particular, the present invention provides a programmable contactless switching device that is particularly well suited for use in elevator systems.
Push-button switches and rotary lever operated switches are common in many different systems. For example, elevator systems employ numerous push-button switches, as well as rotary, key operated switches. Typically, each elevator landing area employs hall call push-buttons. Each elevator car also employs a plurality of push-buttons for allowing passengers to select those floors at which the car should stop and key operated rotary switches for use by elevator service personnel and fire departments. Both the push-buttons and the rotary switches in the prior art employ mechanical contacts. For example, conventional push-buttons typically use standard mechanically operated micro-switches, having mechanical electrical contacts. Usually, the push-buttons contain one or more fixed contacts and a movable conducting bridge that moves as the push button moves, so that when the push button is depressed, the bridge electrically connects or disconnects the fixed contacts to form a closed or opened electrical circuit. Electrical wires connect the push-buttons and the rotary switches to an elevator controller. By opening or closing an electrical circuit, the switches generate signals that can be interpreted by the controller. One shortcoming of these mechanical contact switches is that, over time, the contacts and moving bridge elements wear and can malfunction. For example, push-buttons often get stuck in a closed or opened position and there is no reliable method for determining when a push-button switch needs maintenance.
The present invention provides contactless programmable switching devices. These devices are particularly well-suited for use in elevator systems but may be used in other application that require switching devices. A programmable push-button device according to the present invention comprises a push-button element having an outer surface that an elevator passenger can press with a finger. The push-button element is linearly displaceable between at least a first and second position and is biased toward the first position so that when displaced to the second position it returns to the first position. A magnet is mounted on push-button element. A Hall Effect transducer is located in line with the linear displacement direction of the push-button element. The Hall Effect transducer is located such that when the push-button element is depressed, the magnet moves closer to (or farther away) from the transducer. The Hall Effect transducer is connected to a programmable microprocessor. The microprocessor is capable of being programmed with a unique address. A communication interface for linking the microprocessor to a central computer, such as for example an elevator controller, is connected to the microprocessor.
The present invention may also be employed in a rotary switch. In one embodiment, a plurality of magnets are mounted on a rotatable disk with at least two having their polarities oriented in different directions. A plurality of Hall Effect transducers are located on a surface parallel to the disk. When the rotatable disk is in a first position a first set of the magnets is adjacent to the Hall Effect transducers. As the disk rotates, a second set of magnets, some of which have their polarities oriented differently than those in the first set, becomes aligned over the Hall Effect transducers. The transducers are connected to a microprocessor that can detect changes in the Hall Effect voltages in the transducers. In this embodiment, the switch cannot be activated by placing an external magnet near the device.